Shut Monju down permanently

T he Nuclear Regulation Authority on Wednesday decided to order the Japan Atomic Energy Agency to not engage in further preparatory work to restart the trouble-plagued Monju prototype fast-breeder reactor until the operator improves its safety management to prevent a recurrence of trouble. Monju, located in Tsuruga, Fukui Prefecture, is a core component of Japan’s nuclear fuel cycle project along with the spent nuclear fuel reprocessing plant in Rokkasho, Aomori Prefecture.

Monju has been inoperative for most of the past 19 years while Rokkasho reprocessing plant’s full operation has been postponed 19 times due to a series of problems. Given this troubling history and the JAEA’s slipshod safety management, the logical conclusion should be to decommission the Monju reactor and end the nuclear fuel cycle project. The NRA should unambiguously order the JAEA not to restart Monju.

The NRA pointed out that the JAEA had made light of the need to ensure safety at Monju and failed to inspect nearly 10,000 reactor components in an after 2010. Making matters worse, JAEA head Mr. Atsuyuki Suzuki, who resigned Friday, said that the failure to inspect the components was only a procedural matter and did not cause safety problems. Yet among the components are more than 50 parts vital for the safety of the reactor, including a neutron detector that reveals radiation leaks. His attitude is deplorable.

NRA head Mr. Shunichi Tanaka said that the JAEA lacks a basic understanding of safety. Clearly the JAEA has learned nothing from the Fukushima nuclear catastrophe, which was caused in part by lax management.

The Monju reactor achieved criticality in April 1994 but was shut down in December 1995 due to a sodium coolant leak and fire. Subsequently it was found that the operator tried to cover up the seriousness of the accident. In May 2010, the reactor was restarted but it was halted again before reaching full output because fuel-loading equipment fell into the reactor vessel that August. Nearly ¥1 trillion has been spent on the Monju project. The reactor requires about ¥20 billion in funding annually even while offline.

In a nuclear fuel cycle, uranium and plutonium are extracted through the reprocessing of spent nuclear fuel. A fast-breeder reactor uses plutonium as fuel and theoretically is capable of producing more plutonium than it burns. But the reprocessing also produces highly radioactive waste and the vitrification technology needed to safely store it has not been established. Other countries have abandoned their nuclear fuel cycle projects because of high costs and technical difficulties. Because Monju is offline, the power industry tried to use plutonium separated from spent nuclear fuel in ordinary light water reactors. But this so-called pluthermal approach has hit a snag because of the Fukushima nuclear crisis.

Despite the enormous costs and problems involved in the nuclear fuel cycle project, Prime Minister Shinzo Abe says he will push ahead with the project. He should heed the opinions of the NRA experts and shut this dangerous reactor down.